Can an old gene learn new tricks?

| 2 Comments

From EurekAlert:

The morphological complexity of mammals, as compared to invertebrates, is thought to have arisen through advantageous genetic changes that occurred during the course of evolution. A new research study published in the September issue of Developmental Cell suggests that the evolution of higher-order vertebrate organ systems can result from primitive developmental genetic programs that are, in a sense, recycled for entirely new structures.

According to the expression patterns in the fruit fly, Drosophila, the ancestral action of the Hmx gene was limited to the development of the central nervous system (CNS). Dr. Thomas Lufkin from the Genome Institute of Singapore and colleagues show that the mouse Hmx2 and Hmx3 genes have apparently interchangeable functions in CNS development and have overlapping yet distinct functions in the development of the vestibular system of the inner ear, an organ that has no counterpart in Drosophila. The researchers found that when mice are genetically engineered to lack Hmx2 and Hmx3, Drosophila Hmx can substitute for the mouse Hmx3 gene in CNS development and, surprisingly, can also direct development of the inner ear. Therefore, a Drosophila gene can direct formation of an organ system that does not even exist in the Drosophila body.

“These results demonstrate that the evolution of higher vertebrate characteristics can result from the recycling or redeployment of ‘old’ genes in new parts of the embryo, rather than through mutation of gene protein-coding sequence alone. Old genes can be given a new purpose through ‘reassignment’ to organs undergoing evolutionary advancement. The reassignment likely comes through a shuffling of existing regulatory elements to generate new combinations that are specific to the new organ,” explains Dr. Lufkin.

###

Weidong Wang, J. Fredrik Grimmer, Thomas R. Van De Water, and Thomas Lufkin: “Hmx2 and Hmx3 Homeobox Genes Direct Development of the Murine Inner Ear and Hypothalamus and Can Be Functionally Replaced by Drosophila Hmx”

Developmental Cell, Volume 7, Number 3, September 2004, pages 439-453.

BioMedCentral news report

2 Comments

John M Lynch wrote:

“These results demonstrate that the evolution of higher vertebrate characteristics can result from the recycling or redeployment of ‘old’ genes in new parts of the embryo, rather than through mutation of gene protein-coding sequence alone.

Indeed…

Now all you need to do is explain where the “old” genes came from.

“The wonderful lesson to come out of biology in the last five years is the same genes, the same parts, turn up again and again, from one species to another. The important lesson to realize is that we’re all made of the same fabric, we’re part of the same web, and there’s some humility in the idea that’s appropriate.” Victoria Foe (NYT 8/10/1993)

Charlie Wagner-

Now all you need to do is explain where the “old” genes came from.

By that, I assume you mean what are the origins of deoxyribonucleic acid. The nucelotides that compose DNA are of a nitrogenous base. Nitrogen was in abundance in earth’s atmosphere when these purines began to develop. Through hydrogen bonding, the nitrogen, carbon, oxygen and hydrogen formed the bases for what would later become nucleotides. It’s also important to keep in mind that cellular structure and DNA likely evolved together. The AT and GC combinations that formed strands of DNA and, ultimately, genes, incurred phenotypes in the cells they co-inhabited. Favorable phenotypes helped these early proto-cells to reproduce or replicate more than less favorable phenotypes, encouraging the selection of certain strands of DNA. Over time, those DNA strands became more and more refined into the highly specialized genes we see today.

About this Entry

This page contains a single entry by John M. Lynch published on September 13, 2004 12:16 PM.

The Paradox of Toleration was the previous entry in this blog.

Mathematician, Philosopher, Theologian… Dembski chooses his hat is the next entry in this blog.

Find recent content on the main index or look in the archives to find all content.

Categories

Archives

Author Archives

Powered by Movable Type 4.381

Site Meter